A power supply device in which a plurality of power supplies are combined to supply power to a load is described in, for example, Japanese Patent Laying-Open No. 2010-57288 (PTD 1). The power supply device described in PTD 1 is provided with a switch for switching between series connection and parallel connection of a first power storage unit and a second power storage unit.
PTD 1 describes controlling the power supply device to switch between series connection and parallel connection based on driving power requested by a load, the difference between maximum supply power and total loss in each of a parallel connection state and a series connection state, as well as total loss. Thereby provided is a power supply device capable of achieving request driving power as much as possible in all usage conditions of the load, while reducing total loss to improve mutual efficiency.
Japanese Patent Laying-Open No. 2012-70514 (PTD 2) describes a configuration of a power converter capable of, by means of controlling of a plurality of switching elements, switching between an operation mode of carrying out DC/DC conversion with two DC power supplies connected in series (series connection mode) and an operation mode of carrying out DC/DC conversion with the two DC power supplies used in parallel (parallel connection mode).